1. Field of the Art
The present invention relates to a plastic product such as a pump casing used in a high speed/high pressure rotary machine, and a method for manufacturing such a plastic product.
2. Prior Art
Since a high pressure rotary machine of this kind normally generates a great amount of vibration and noise, it is necessary for parts of the rotary machine such as a casing and an impeller to have vibration preventing properties and noise attenuation properties. Conventionally, in order to prevent or attenuate vibration and noise, machine parts have been formed from vibration suppressing materials and/or noise shielding materials. However, the volume of such part tends to become bulky, and, it is therefore, difficult to produce a part having a complicated configuration due to the poor workability of materials used. Further, since frequencies for attenuating vibration and noise differ from material to material, it is difficult to set an attenuating frequency for a part.
Further, the fiber-reinforced plastic (in which glass fibers or carbon fibers are mixed with plastic) is often used to form parts of a high pressure rotary machine from a plastic material. In this case, if the part has a complicated shape, since a structure of a die for manufacturing the part also becomes complicated, it is very difficult to form the complicated part from the plastic material.
The present invention was made to overcome the above-mentioned conventional drawbacks, and has as an object the provision of a plastic product which is light-weight, strong and has excellent vibration suppressing and noise shielding characteristics, and a method for manufacturing such a plastic product, in which a complicated shape can be easily obtained.